In short: a lady-bro is a bro's girlfriend who is also chill and can participate in bro-night, pending approval by the other bros.

Further exegesis:
A lady-bro is, first and foremost, chill. She is able to hold her own in the company of all males. She can relate to conversation at bro-night and can even offer further stimulation to the gathering. However, this characterization is not sufficient for the definition of a lady-bro!

She is more than just a girl who is refreshingly easy to hang out with. She is the girlfriend of a bro who is ALSO easy to hang out with. That is, she is allowed to come to bro-night and drink some bro-sodas (though whether the term bro-soda can be used in her presence is debatable--see entry for bro-soda).

a chick thatz not exactly bro hoe but she fitz into the category of a offroader..
she datez bros, lady bros dont like to hoe around or smoke weed..
They usually wear srh, tapout ,alpinestars, fox, Socal or Nocal, Hostility, infamous, metal mulisha, skin-these girlz usually have blonde n black hair.. or sometype of fantasy color in their hair..
-these femalez are hard.. n down for their shit they DGAF
-Lifted truckz, quadz and dirt bikez are a neccessity
-usually listen to rock n kottonmouth kingz
these girlz are not ignorant..
they are actually very intelligent..
THESE FEMALES ARE HOTTTT